As a current-mode light emitting device, an organic light emitting diode (referred to as OLED) is increasingly applied to a high-performance display field due to its characteristics of self-luminescent, fast response, wide viewing angle and available to be manufactured on a flexible substrate, etc. The OLED can be divided into two kinds of a passive matrix driving OLED (referred to as PMOLED) and an active matrix driving OLED (referred to as AMOLED) according to driving modes. As the display apparatus increases in size, a conventional PMOLED needs to reduce driving time of a single pixel, and thereby it needs to increase transient current, thus resulting in a rise of power consumption; at the same time, it would make an operating voltage of OLED become over high, thereby causing a decrease of working efficiency. Whereas in AMOLED technique, each OLED scans input current through a thin film transistor (referred to as TFT) switching circuit progressively, this can solve the above problem well.
In the existing AMOLED panel, the TFT switching circuit adopts mostly a low temperature poly silicon thin film transistor (LTPS TFT) or an oxide thin film transistor (Oxide TFT). Compared with a common amorphous-silicon thin film transistor (amorphous-Si TFT), LTPS TFT and Oxide TFT have higher mobility rate and more stable characteristics, and are more suitable for being applied in AMOLED display. However, due to limitations of crystallization process and production level, non-uniformity in electrical parameters such as threshold voltage and mobility rate and so on always occurs to the TFT switching circuits manufactured on a large-size glass substrate, such that threshold voltage offset of respective TFTs is inconsistent; in addition, under long-time pressure and high temperature, it would also cause occurrence of the threshold voltage drift of the TFT. Threshold drift of TFTs in different parts of the panel would be different because of different display pictures, thereby causing differences in display luminance. As a result, phenomenon of image sticking would occur. Further, it would cause the current for driving a diode unstable, thereby causing luminance difference of OLED display devices, such that the problem of non-uniformity of luminance would occur, and the display effect of a display device would be influenced.